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CVE-2026-64044— ovpn: respect peer refcount in CMD_NEW_PEER error path

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于在CMD_NEW_PEER错误路径中未正确处理peer引用计数，调用ovpn_peer_release()直接释放而非通过ovpn_peer_put()，导致TCP连接上已持有引用的用户态调用者可能在free后内存上继续操作，最终造成释放后重用。以下版本受到影响：6.16版本。

CVSS 7.8 · High EPSS 0.18% · P8

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 11851cbd60ea1e5abbd97619d69845ead99303d6< 8298834912d76dbc82c12b6b4ab7590ed2bb8ae5 affected
11851cbd60ea1e5abbd97619d69845ead99303d6< 0c3ef71879c0264de6c42463031d9e057da87840 affected
11851cbd60ea1e5abbd97619d69845ead99303d6< 1fef6614673ff0846d30acdeeaf3cf98bb5f6116 affected
6.16 affected
< 6.16 unaffected
6.18.34≤ 6.18.* unaffected
7.0.11≤ 7.0.* unaffected
7.1≤ * unaffected
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I. Basic Information for CVE-2026-64044

Vulnerability Information
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Vulnerability Title
ovpn: respect peer refcount in CMD_NEW_PEER error path
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ovpn: respect peer refcount in CMD_NEW_PEER error path ovpn_nl_peer_new_doit()'s error path calls ovpn_peer_release() directly rather than ovpn_peer_put(), bypassing the kref. The accompanying comment ("peer was not yet hashed, thus it is not used in any context") holds for UDP but not for TCP. For UDP, the ovpn_socket union uses the .ovpn arm and never points back at a peer; UDP encap_recv looks up peers via the not-yet-populated hashtables, so the new peer is unreachable until ovpn_peer_add() publishes it. For TCP, ovpn_socket_new() sets ovpn_sock->peer and ovpn_tcp_socket_attach() publishes ovpn_sock via rcu_assign_sk_user_data(). From that moment until ovpn_socket_release() detaches in the error path, the TCP fd is fully wired: userspace recvmsg / sendmsg / close / poll on the fd, as well as the strparser-driven ovpn_tcp_rcv() path, can reach the peer through sk_user_data -> ovpn_sock->peer and bump its refcount via ovpn_peer_hold(). ovpn_tcp_socket_wait_finish() (called inside ovpn_socket_release()) drains strparser and the tx work, but does not synchronize with userspace syscall callers that already hold a peer reference. If ovpn_nl_peer_modify() or ovpn_peer_add() returns an error while such a caller is in flight - notably an ovpn_tcp_recvmsg() blocked in __skb_recv_datagram() on peer->tcp.user_queue - the direct ovpn_peer_release() destroys the peer while the caller still holds the reference, and the eventual ovpn_peer_put() from that caller operates on freed memory. Replace the direct destructor call with ovpn_peer_put() so the kref correctly defers destruction until the last reference is dropped. In the common case where no concurrent user is present, behaviour is unchanged: the kref hits zero immediately and ovpn_peer_release_kref() runs the same destructor. With this conversion ovpn_peer_release() has no callers outside peer.c - ovpn_peer_release_kref() in the same translation unit is the only remaining user - so make it static and drop its declaration from peer.h.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于在CMD_NEW_PEER错误路径中未正确处理peer引用计数，调用ovpn_peer_release()直接释放而非通过ovpn_peer_put()，导致TCP连接上已持有引用的用户态调用者可能在free后内存上继续操作，最终造成释放后重用。以下版本受到影响：6.16版本。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 11851cbd60ea1e5abbd97619d69845ead99303d6 ~ 8298834912d76dbc82c12b6b4ab7590ed2bb8ae5 -
Linux Linux 6.16 -

II. Public POCs for CVE-2026-64044

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III. Intelligence Information for CVE-2026-64044

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Patches & Fixes for CVE-2026-64044 (2)

Same Patch Batch · Linux · 2026-07-19 · 429 CVEs total

CVE-2026-63795 10.0 CRITICAL 9p: avoid putting oldfid in p9_client_walk() error path
CVE-2026-64033 9.8 CRITICAL RDMA/rtrs: Fix use-after-free in path file creation cleanup
CVE-2026-63994 9.8 CRITICAL tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()
CVE-2026-63993 9.8 CRITICAL vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()
CVE-2026-64142 9.8 CRITICAL ksmbd: close durable scavenger races against m_fp_list lookups
CVE-2026-64102 9.8 CRITICAL RDMA/siw: Reject MPA FPDU length underflow before signed receive math
CVE-2026-53399 9.8 CRITICAL nfsd: release layout stid on setlease failure
CVE-2026-53398 9.8 CRITICAL NFSD: Fix SECINFO_NO_NAME decode error cleanup
CVE-2026-64061 9.8 CRITICAL netfs: Fix early put of sink folio in netfs_read_gaps()
CVE-2026-64089 9.8 CRITICAL batman-adv: tt: fix negative last_changeset_len
CVE-2026-64091 9.8 CRITICAL batman-adv: tt: fix TOCTOU race for reported vlans
CVE-2026-64025 9.8 CRITICAL bpf, skmsg: fix verdict sk_data_ready racing with ktls rx
CVE-2026-64125 9.8 CRITICAL net: bcmgenet: keep RBUF EEE/PM disabled
CVE-2026-64066 9.8 CRITICAL netfs: Fix netfs_read_to_pagecache() to pause on subreq failure
CVE-2026-64132 9.8 CRITICAL ipv6: ioam: refresh hdr pointer before ioam6_event()
CVE-2026-64136 9.8 CRITICAL smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()
CVE-2026-63979 9.8 CRITICAL net/handshake: hand off the pinned file reference to accept_doit
CVE-2026-63887 9.8 CRITICAL scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
CVE-2026-63978 9.8 CRITICAL net/handshake: Drain pending requests at net namespace exit
CVE-2026-63808 9.8 CRITICAL exfat: fix potential use-after-free in exfat_find_dir_entry()

Showing top 20 of 429 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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